1. Field of the Invention
The present invention relates to a magnetic tape apparatus, particularly to a magnetic tape apparatus having a cylinder motor for driving a rotation cylinder containing a magnetic head and around which a magnetic tape is wound and a capstan motor for driving a capstan which applies a feeding force to the magnetic tape.
2. Description of the Related Art
A conventional magnetic tape apparatus of this type is shown in FIG. 5. In this drawing, symbol C designates a tape cassette having a feed reel C1 and a winding reel C2. The feed reel C1 and the winding reel C2 are set on reel tables 1a and 1b, respectively. Reference numeral 2 designates a movable loading post 2 which is provided so as to draw a tape T from the tape cassette C and winds the tape around a rotation cylinder 3 containing a magnetic head therein. Reference numeral 4 designates an entire width erasing head, reference numeral 5 designates an audio erasing head and reference numeral 6 designates an audio control head. Reference numeral 7 designates a tape guide post being fixed, reference numeral 8 designates a tension post for applying a tension force to the tape T being loaded, reference numeral 9 designates a capstan for applying a running force to the tape T, reference numeral 10 designates a pinch roller, reference numeral 11 designates an arm, reference numeral 12 designates a supporting shaft of the arm and reference numeral 13 designates a rotation cam. The rotation cylinder 3 illustrated by a phantom line contains a magnetic head (not shown) therein and is rotated in one direction by a cylinder motor 20. The capstan 9 is rotated in one direction by a capstan motor 30.
In the conventional magnetic tape apparatus which is separately provided with the cylinder motor 20 and the capstan motor 30, the cylinder motor 20 has a relatively large circular opening 22 at the center portion of a stator core 21. The circular opening 22 defines a space for disposing a constituent part of the cylinder motor 20, for example, a disk-shaped pressurizing member for pressurizing a bearing member which supports a rotation shaft of the rotation cylinder 3. Incidentally, a reference numeral 23 designates a rotor of the cylinder motor 20.
On the other hand, the capstan motor 30 includes a stator core 31 and a bearing holder 41 which are configured as illustrated in FIGS. 6 to 8. As shown in FIG. 6, the bearing holder 41 is formed by a cylindrical resin mold member for holding a bearing 42 formed by oil-bearing metal therein and is provided with a flange-shaped attachment portion 43 which is disposed concentrically. At each of three portions disposed with the same angular interval along the circumferential direction of the flange-shaped attachment portion 43, a recess portion 44 is formed such that the width thereof becomes smaller toward the center of the bearing holder 41. In contrast, the stator core 31 is provided with three plate-shaped attachment pieces 32 which are disposed with the same angular interval along the circumferential direction of the stator core and each of which extends inward toward the center of the stator core such that the width thereof becomes smaller toward the center of the stator core. As shown in FIG. 6, each of the attachment pieces 32 is fitted into the corresponding one of the recess portions 44 of the flange-shaped attachment portion 43 such that the attachment piece 32 fitted into the recess portion 44 is sandwiched by both side wall surfaces 45, 45 forming the corresponding recess portion 44, whereby the stator core 31 is positionally restricted in the circumferential direction thereof with respect to the bearing holder 41. An arc-shaped inner end 33 of each of the attachment pieces 32 engages with the outer peripheral surface 46 of the bearing holder 41, so that the stator core 31 is positionally restricted in the radial direction thereof with respect to the bearing holder 41. The flange-shaped attachment portion 43 and the attachment pieces 32 positionally restricted in the circumferential and radial directions thereof in this manner are coupled by means of attachment screws 35 which are respectively inserted into screw insertion holes 47 provided at the flange-shaped attachment portion 43 and screwed into screw holes 34 provided at the inner end portions of the attachment pieces 32.
In the aforesaid conventional magnetic tape apparatus, since the cylindrical-shaped bearing holder 41 is molded by composite resin, if the thickness of the bearing holder 41 is made too large, a so-called sink mark or sink due to the molding is likely generated, so that the accuracy of the size and appearance of the bearing holder may be degraded. Thus, the enlargement of the diameter of the outer periphery of the bearing holder 41 is limited. Further, since the stator core 31 of the capstan motor 30 is required to be attached to the bearing holder after positioning the stator core concentrically with respect to the bearing holder 41, the inner end 33 of each of the attachment pieces 32 is made engage with the outer peripheral surface 46 of the bearing holder 41 thereby to positionally restrict the stator core in the radial direction thereof.
In the aforesaid conventional magnetic tape apparatus, same plate-shaped metal member is used for the stator core 31 of the capstan motor 30 and the stator core 21 of the rotation cylinder 3. Thus, if the diameter size d1 of a phantom circle “a” shown in FIG. 9 formed by the inner ends 33 of the three attachment pieces 32 provided at the stator core 31 of the capstan motor 30 can be made equal to the diameter size D of the circular opening 22 provided at the stator core 21 of the rotation cylinder 3 explained with reference to FIG. 5, the common die can be employed for the stamping process used at a portion surrounded by the phantom line “a” on the stator core 31 side of the capstan motor 30 and for the stamping process used at the circular opening 22 on the stator core 21 side of the rotation cylinder 3, whereby manufacturing cost can be suppressed. In other words, a so-called family processing becomes possible that the portion surrounded by the phantom line “a” and the circular opening 22 are stamped using the same die, which results in the suppression of the manufacturing cost.
On the other hand, JP-A-10-336941 discloses such a structure that the inner peripheral surface of a circular opening of a stator core fitted into a bearing holder is overlapped on the outer peripheral surface of the bearing holder.
Further, JP-A-2000-166164 discloses a motor for rotationally driving a disk in which a stator core is attached to a bearing holder. A core holder is fixed to the bearing holder. The stator core is overlapped on the core holder and they are coupled to each other via a U-shaped stopper.
In the conventional magnetic tape apparatus, the enlargement of the diameter of the outer periphery of the bearing holder 41 is restricted in a viewpoint of the molding technique. Further, since such a configuration is employed that the inner end 33 of each of the attachment pieces 32 is made engage with the outer peripheral surface 46 of the bearing holder 41 thereby to positionally restrict the stator core in the radial direction thereof, the diameter size d1 of the phantom circle “a” on the stator core 31 side of the capstan motor 30 is required to be shorter than the diameter size D of the circular opening 22 on the stator core 21 side of the rotation cylinder 3. As a result, there arise a problem that the suppression of the manufacturing cost employing the aforesaid family processing can not be realized.
Since JP-A-10-336941 employs the structure that the inner peripheral surface of the circular opening of the stator core is overlapped on the outer peripheral surface of the bearing holder thereby to positionally restrict them concentrically, the aforesaid problem of the conventional magnetic tape apparatus can not be solved.
Further, JP-A-2000-166164 has a problem that the stopper is additionally required and so the number of parts increases, which impede the reduction of the manufacturing cost.